Combined wet and dry quenching

ABSTRACT

COKE FROM A HORIZONTAL COKE OVEN IS PUSHED INTO A GUIDE CASING, FROM WHICH IT FALLS INTO A COOLING CHAMBER. AFTER THE INLET TO THE CHAMBER HAS BEEN CLOSED THE COKE IS SPRINKLED WITH WATER TO REDUCE ITS AVERAGE TEMPERATURE TO BELOW ABOUT 600*C, FOLLOWING WHICH AN INERT COOLING GAS IS PASSED THROUGH THE COKE TO FURTHER REDUCE ITS TEMPERATURE TO ABOUT 200*C AND THEN THE QUENCHED COKE IS DISCHARGED FROM THE CHAMBER.

May 7, 1.974

FRIEbRlCH-WILHELM DREBES ETAL 3,809,619

COMBINED WET AND DRY QUENCHING Sheets-Sheet 1.

Filed May 17 1972 May 1974 FRIEDRICH-WILHELM DREBES A 3'809619 COMBINED WET AND DRY QUENCHING F y 1972 3 Sheets-Sheet 2 Fig. 3

7, 1974 FRIEDRICH-WILHELM DREBES ETAL COMBINED WET ANDDRY QUENCHING Filed y 9 I 3 Sheets-Sheet 3 United States Patent Oflice' 3,809,619 Patented May 7, 1974 3,809,619 COMBINED WET AND DRY QUENCI-IING Friedrich-Wilhelm Drebes, Bochum-Dahlhausen, and Gunter Birreshorn, Bochum, Germany, assignors to Dr. C. Otto & Comp., G.m.b.H., Bochum, West Germany Filed May 17, 1972, Ser. No. 254,087 Int. Cl. (11% 39/00 US. Cl. 20139 5 Claims ABSTRACT OF THE DISCLOSURE Coke from a horizontal coke oven is pushed into a guide casing, from which it falls into a cooling chamber. After the inlet to the chamber has been closed the coke is sprinkled with water to reduce its average temperature to below about 600 C., following which an inert cooling gas is passed through the coke to further reduce its temperature to about 200 C. and then the quenched coke is discharged from the chamber.

With the majority of currently operated coke producing installations, coke first is pushed from the ovens into a quench car and then is taken in the car to a quench tower. During the pushing of the coke, a large amount of dust is formed which causes considerable damage in residential areas. Also, the vapor that ascends from a quench tower contains large quantities of solids which are carried along with it, and also toxic substances that pollute the atmosphere. Thus, to an ever-increasing extent, municipalities and other governmental bodies require that pollution due to coke pushing and quenching be avoided as much as possible.

In the use of apparatus for the so-called dry cooling of coke, cooling chambers corresponding in capacity to the volume of coke coming from an oven are provided for a coke oven battery. Three adjacent oven chambers may be provided with a common cooling chamber. The cooling for a chamber charge lasts approximately one-third of the operating time for the oven. The glowing coke cake that is discharged from a furnace chamber is guided to the opened trap door of the related cooling chamber and drops into the chamber. The chamber also is provided with a closeable inlet and outlet for gases or vapors. After the inlet and outlet have been opened and the trap door is closed, an inert gas is directed through the chamber. In cooling the coke, this gas is heated and then piped to a steam boiler. A blower maintains the circulation of the inert gas. Such installations have operated perfectly, but the coke heat that was converted into steam cannot be utilized economically in many plants. Moreover, when a customer does not accept coke because of its low water content, there is the loss of the sale. In addition, no provision has been made for means to avoid the formation of dust clouds when the hot coke is pushed into the cooling chambers.

The present invention relates to a process in which cooling chambers, such as are employed with the abovementioned dry coke cooling, are used. They are suitable for receiving the hot coke from oven chambers and are provided with closeable inlets and outlets for gases or vapors, by means of which heat exchange with the pushed coke is produced to cool the coke. In addition, a guide unit is provided for conducting the hot coke between the ovens and the cooling chambers, this guide unit providing a smoke-tight connection between an oven door and the trap door or coke inlet of a cooling chamber. Thus, formation of smoke is avoided during emptying of the oven chamber.

After the cooling chamber has been filled with hot coke, the coke is first sprinkled with water to such an extent that its average temperature is reduced below about 600 C. It is then at a temperature where there is little chance of it igniting. Inert gas then is passed through the coke to achieve further cooling of the coke down to about 200 C. The coke then is removed from the chamber and carried away in a known manner.

This process can be carried outwith different inert gases, so that gases that are available at the particular coke oven installation can be used for the cooling. For example, a part of the waste gas of the coke oven battery can serve as the inert gas after it has been cooled to a sufliciently low temperature of about 50 C., for example, by sprin kling it with water. The cooled waste gas then is directed into the cooling chambers so that it will flow through the hot coke in them. After the inert gas leaves the cooling chambers and passes through apparatus for removing solids from it, it is directed into a flue along with the other waste gases. On the other hand, it is not always necessary to use new waste gas for the heat exchange in the cooling chambers. Thus, after the inert gas leaves the cooling chambers a part of it can be cooled again by sprinkling with water and returned to the cooling chamber.

In the case of an oven battery that is charged with preheated coal, the hot air of the preheating installation may be used as the inert gas.

If desired, the coke oven battery can be operated in such a way that a fiue for the discharge of its waste gases is unnecessary. The entire waste gas can be drawn off by means of a blower, cooled sufiiciently, and then directed through the cooling chambers, after which solids are removed from the gas and it is delivered to the atmosphere. Such a process has several advantages. Thus, the stack, for which regulations are constantly requiring greater dimensions relative to height, can be eliminated. The ovens are operated with an induced draft. Consequently, variations in stack draft that are due to atmospheric influences no longer occur, whereby an especially uniform oven operation can be achieved. It also is possible to obtain a better heat recovery from the waste gases. With the use of the stack draft, there is a limitation relative to the lowest temperature in the regenerators, due to the fact that it is not possible to fall beow the dew point of the waste gas in the stack. On the other hand, if an induced draft is used, an extensive heat exchange is possible in the regenerator. Falling below the dew point is avoided in any case by the heating of the waste gases in the cooling chambers.

It is among the objects of this invention to provide a coke quenching process that avoids pollution due heretofore to coke pushing and quenching.

The invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a fragmentary plan view showing a battery of coke ovens in horizontal section;

FIG. 2 is a vertical section taken substantially on the line IIII of FIG. 1;

FIG. 3 is a diagram of a coke cooling system with a waste gas partial flow; and

FIG. 4 shows a modification by means of a section similar to FIG. 2 and a schematic representation of the elements needed for heat exchange.

Referring to FIGS. 1 and 2 of the drawings, in front of a battery of horizontal coke ovens 1 a coke oven guide car 2 runs along a track 3 that straddles a row of trap doors 4 at the upper ends of a row of cooling chambers 5. These doors normally close the coke inlet openings 6 of the chambers. The car carries a guide casing 8 that is open at one side to fit around the open door of any of the coke oven chambers. The bottom of the casing likewise is open, and the car has a passage 9 leading from the bottom opening down to an underlying cooling chamber inlet 6. When a coke pusher 10 pushes coke out of an oven into the guide casing, the coke falls into the underlying cooling chamber, the trap door of which has first been opened. The pusher only needs to move up to the opening into the guide casing, so that push rod can be made shorter than for installations using a standard coke quench car. Pollution of the atmosphere by smoke and dust is avoided because the passage from the oven to the cooling chamber is closed by the guide casing. When the hot coke enters the cooling chamber itslides down the inclined perforated bottom 11 of the chamber and is stopped at the lower end by a closed discharge door. 12. As soon as the coke pusher has been withdrawn, the door 4 for the cooling chamber inlet is replaced to seal the chamber.

The coke now is ready to be quenched. This process is started by sprinkling it with water from a number of nozzles 14 carried by a high pressure water pipe 15 above the top wall of the cooling chamber. The nozzles extend down into openings 16 through the top wall. The quantity of water used is adjusted so that the coke is cooled to a temperature between about 500 C. and 600 C. The average temperature of the coke should be below about 600 C. The steam that is formed by the water sprinkled on the hot coke dilutes the gas which is released into the chamber with the falling apart of the coke, and thereby explosions are prevented. Due to the cooling of the coke below 600 C., combustion and gas reactions are sufiiciently supressed or prevented.

At the time the sprinklers are turned on a closed valve 18 above the cooling chamber is opened. This valve is in a large pipe 19 that connects an outlet opening 20 near the upper end of the chamber with a collecting pipe 21, to which similar hot gas pipes from the other oven chambers also are connected. The apparatus to which the collecting pipe leads will be described presently.

As soon as the sprinkling apparatus is turned off, a closed cooling gas valve 23 beneath the lower end of the chamber is opened. This valve opens into a space 24 below the perforated bottom of the cooling chamber. The inlet of the valve is connected with a gas passage 25 that receives waste gas from the oven battery. This inert gas is cooled before it reaches the valve, in a manner about to be described, and is forced up through the valve and the coke in the cooling chamber by means of a blower until the coke is cooled to approximately 200 C. Now the coke is removed from the cooling chamber by opening its discharge door 12 at its lower end. This can be opened only if the cooling gas valve 23 and the hot gas valve 18 are closed. The coke is discharged through the door into an enclosed chute 26 that deposits the coke uniformly on a belt conveyor 27 where the coke can cease steaming. If disturbances occur in the cooling system, it is possible to cool the coke below the still admissible temperature by means of sprinkling apparatus 28 located at the exhaust hood of the discharge chute. By means of this secondary quenching apparatus it is also possible to increase the water content of the coke if this is desired for economic reasons. The vapors that are formed by the secondary quenching are exhausted through a special exhaust line 29 (FIG. 2) and are de-dusted and directed into the smoke channel that leads to the stack. The bottom of the chute can be designed as a screen so that the coke breeze can'be screened out and removed by means of a special belt conveyor (not shown) below the chute.

The inert gas that is 'delivered to gas passage 25 and the cooling chambers is drawn out of the smoke channel 31 of the installation by means of a suction blower 32. The gas is drawn through a throttle valve 33 and a cooler 34, in which it is cooled to approximately 50 C. by water sprinkled from a nozzle 35 in the upper end of the cooler. The hot gas that leaves through the collecting pipe 21 is delivered to a cyclone 37, in which coke particles and coarse dust that have ben carried along with it are separated. The outlet of the cyclone is connected by a pipe 38 to a boiler or heat exchanger 39, where heat from the gas can be recovered. After the gas leaves the heat exchanger, part of it enters a fine cleaning apparatus 41, an electro-filter or a wet de-duster and is discharged through a pipe 42 to the smoke channel 31 that leads to the stack 43. The gas that did not enter the fine cleaning apparatus is recycled through a pipe 44 and a throttle valve 45 back to the cooler 34. This portion of the inert gas that remains in the cycle can be adjusted relative to the newly introduced waste gas by adjusting the two throttle valves 33 and 45.

If there is a coal preheating installation for the coke ovens, the steam from this installation can be used as an inert gas. Since large quantities of steam are constantly available in such an installation, recycling of part of the steam is not necessary. The entire amount of steam and vapors is cleaned and discharged through the stack.

In the modification shown in FIG. 4, all of the waste gas from the coke oven battery 50 is sucked from the smoke channel 51 by an induced draft suction blower 52 and forced through a cooler 53, where the gas is cooled by Water. The suction from the smoke channel is adjusted by means of a throttle valve 54 to give the correct draft. The cooled gas leaves the cooler and is conducted through a line 56 back to the inlet valve 57 of a coke cooling chamber 58. The coke cooling process by Water and inert gas is the same as described in connection with FIGS. 1 to 3. All of the hot gas leaving the cooling chambers through a valve 59 and a pipe 60 is directed into a cyclone 61 and then passes through a fine cleaning apparatus 62 and escapes through a low stack 63 into the atmosphere. If desired, a boiler or heat exchanger can be connected in the line between the cyclone and the fine cleaning apparatus in order to recover heat from the gas.

According to the provisions of the patent statutes, we have explained the principle of our invention and have illustrated and described what We now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. A process for quenching coke in a cooling chamber that has an inlet for receiving coke through a guide casing from a horizontal coke oven battery, comprising closing the coke inlet of the chamber, sprinkling the coke in the chamber with water to reduce its average temperature to below about 600 C., then passing an inert cooling gas through the coke to further reduce the temperature of the coke to about 200 -C., conducting said gas away from the coke, and finally discharging the coke from the chamber.

2. A process according to claim 1, including sprinkling hot waste gas from said oven battery with water to reduce its temperature to about 50 C. for use as said inert cooling gas, conducting said cooled gas to the cooling chamber, separating solid particles from the gas leaving the chamber, and delivering the cleaned gas to the atmosphere.

3. A process according to claim 2, in which part of said inert gas that has left the cooling chamber is sprinkled with water to cool it and then is forced back through the cooling chamber.

5 6 4. A process according to claim 2, in which substan- 1,898,267 2/1933 Schaefer 202-228 tially all of the hot waste gas from said oven bigcry is 1,464,732 8/1923 Stafford 201---39 drawn off, cooled, directed through said cooling c amber, cleaned of solid particles and discharged into the atmos- FOREIGN PATENTS h 6 517,066 5/1931 Germany 202-227 5. A process according to claim 1, including preheating coal before it is charged into the oven, and usin'gf'steam NORMAN YUDKOFF, Pnmafy Elamlnel produced y said preheating as said inert wvling gas. D. EDWARDS, Assistant Examiner References Cited 10 us Cl. X R UNITED STATES PATENTS 202-227, 228

1,557,077 10/1925 Moetteli 202228 

